Where There’s Muck …
Airedale might sound bucolic but the low end of it is a roll call of old Yorkshire centres of smoke and grime – Keighley, Bradford, Leeds – and the shape and angle of the dale mean it gets less than its fair share of sunlight anyway.
In this unpromising horticultural location, Jack First has been sowing salads in January and reaping from late March for some time now – a timetable which will make any gardener sit up and take notice.
You might have seen him talking about it on Gardeners’ World. Now he has written a book which explains how he does it, and how you can have a go too.
Its credits go back to the days of the Roman Empire, when Italian generals, posted to northern Europe, yearned for vegetables made from warmth and must have noticed how stray seeds of all sorts would shoot defiantly out of rotting manure in all seasons.
As far as Mr First can trace the story back, it was the Emperor Tiberius, during a campaign in Germany, who founded the science of growing in “hot beds”. It was a technique still widely used a century ago and the Lost Gardens of Heligan, in Cornwall, revived it recently for an experiment in growing pineapples in Victorian-style glasshouses. They harvested the first just before Christmas, from a crop of eight which were estimated to have cost £1,200 each.
That would be building and labour costs, however. In fossil fuel consumption, the Cornish pineapples were more or less free. And now that we are costing everything in terms of carbon burnt, Jack First argues that there are serious commercial possibilities in hot-bedding once again.
Meanwhile, he can tell you how to get a lot of fun out of trying it on a small scale, to produce the kind of early salads he sells at a premium through a community shop in Bradford.
Less than a hundred years ago, he points out, greens forced in hot beds were quite a big business. The French specialised in them and sold them to the English by the ton, and it was an old book called The French Garden In England which got Mr First interested.
Even in Airedale, between Keighley and Bradford, after 15 years of experimentation and measurement, he reckons t is possible to get an advantage on the natural growing season of a thousand hours of sunshine.
On its own, English winter sunshine is not enough to sustain delicate seedlings. But with heat coming up from the ground too, its weak value can be usefully extracted from soon after the winter solstice, in December.
The best hot-bed material always was bedding from horse stables – the perfect mix of manure, straw and urine. It still is, says Mr First, but the composition of the straw has changed, because of combine harvesting, and he has had to recalculate most of the old guidance on the timing of decomposition and the strength of the heat generated. And other materials, including wet leaves and waste wool, run it close.
Any material which rots fast enough to be useful will get too hot for plant life at first. The growing frames must be set on top of the fermentation material, or surrounded by it, and filled with a stable mixture which will draw heat but not create it. Even then the grower has to put in a lot of work to keep control of the temperature in the growing medium – checking it with a thermometer and lifting off the roof lights as required. But all this could be automated.
Once the initial rot is over, the used heating material makes a good compost to mix into the next year’s growing beds.
Meanwhile, while hot, it acts as a barrier to pests and gives enough kickstart for several crops at a time, says the book. Jack First usually has lettuces following radishes and followed by carrots, all planted at the same time but maturing one after the other. The carrots will be ready in May, with cauliflowers close behind, grown from seeds which were started indoors in October. He crops potatoes over April and May and tomatoes in July. The final flourish of the year is a melon crop from a combination of hot beds and polytunnel.
His experiments include producing hot water at the same as the crops, using pipes in the soil. One way and another, he argues, the system can be adapted to give value from a range of possible materials in a range of circumstances.
He says: “It went with having a lot of horses around. But then the motor car started to edge out the horse and with gas and electricity it was relatively cheap to heat soil with cables or keep a glasshouse full of warm air. Now fossil fuels are getting progressively more expensive and as I say in the book, my work has shown that there are plenty of possibilities besides stable muck.”
Mr First, 61, lives in Hipperholme, near Halifax, and runs teaching and work experience at allotments belonging to the Cellar Project, a Bradford-based charity. But he is available to run courses and give talks for anyone else interested – email@example.com/
Hot Beds: How to Grow Early Crops Using an Age-Old Technique, by Jack First, is published by Green Books (RRP £9.95, paperback) and is available from greenbooks.co.uk/hot-beds/
Possible panel …
Hot tips …
If you want to shift a lot of dung, buy a dung fork.
Look out for obstructions which might get in the way of low-hanging winter suns.
Minimum useful size for a hot bed is about six-foot (180 cms) square. It will need to be at least two feet (60cms) deep to keep working from January to late March but you can get away with less for a later start.